1. Field of the Invention
The present invention relates to a data processing apparatus, such as an AV (audio/video) server for television broadcasts or a non-linear editor, where a non-linear recording medium is accessed from two or more input/output ports to record and/or play back video data.
2. Description of the Related Art
AV servers and non-linear editors with a plurality of input/output ports and a large-capacity recording medium (such as a hard disk drive or flash memory) as main storage that is capable of non-linear access are getting more widespread as appliances that allow AV data to be recorded, played back, and edited for television broadcasts.
In an AV server or non-linear editor, to prevent all of the plurality of input/output ports from accessing the main storage at the same time, access to the main storage from the respective input/output ports is normally managed using time slots (see, for example, Japanese Unexamined Patent Application Publication No. 2000-307978 (Paragraphs 0008, 0046, and 0047)). Also, to make it possible for each input/output port to input and output AV data at a predetermined rate irrespective of such time slots, a memory is provided for temporarily storing AV data during recording and playback into and from the main storage.
FIG. 1 is a diagram schematically showing one method of managing a memory used to temporarily store AV data in an AV server or non-linear editor of the related art. For example, if there are five input/output ports numbered Port #1 to Port #5, the entire storage region of the memory M is divided into and managed as five regions M1 to M5 that are dedicated to the ports Port #1 to Port #5.
When AV data is inputted into the input/output port Port #1, the AV data is written for each frame into the region M1 of the memory M. When a predetermined amount of AV data has accumulated in the region M1, the AV data in the region M1 is recorded in the main storage MS at the timing of a time slot assigned to the input/output port Port #1.
In the same way, when AV data is outputted from the input/output port Port #2, AV data inside the main storage MS is written into the region M2 of the AV data memory M at the timing of the time slot assigned to the input/output port Port #2. Each frame in the AV data written into the region M2 is outputted from the input/output port Port #2. The same process is also carried out for the input/output ports Port #3 to Port #5.
However, the functions of an AV server and a non-linear editor include a function called “chasing playback” where AV data inputted into a given input/output port is immediately outputted from another input/output port. As examples, chasing playback is used when replaying highlights during a live sports broadcast and when editing AV data shot on-location during a news program.
When an AV server or non-linear editor carries out chasing playback, AV data that has been recorded in the main storage is played back and outputted.